In Syntorial V2 the Unison Spread knob jumps between values 0 and 1. This is by design. However, in version 2.0.007 and earlier, there's a bug in which a few lessons expect you to set it to the middle 0.5 value. If you experience this, simply update to the latest version:
Mac/Windows
- Log into your online account.
- In the Syntorial section select “Downloads”
- Download and install the latest version
iPad
- Download the latest version from the App Store